Existing instruments for automatic micromeasurement normally employ either video scanning or photometric slit scanning techniques. The video scanning technique suffers from non-linearities inevitably present in the scanning of a television camera tube, whereas the photometric slit scanning technique suffers from the disadvantage of being slow in operation.
The present invention has therefore been developed primarily, though not exclusively, with a view to providing a micromeasurement method and apparatus that is faster in operation than the photometric slit scanning technique, and yet which overcomes the potential inaccuracies of the existing video scanning technique.